Electric switch construction



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INVENTOR John 6: Jackson ATTORNEYS Patented Mar. 13, 1934 PATENT OFFICE ELECTRIC SWITCH CONSTRUCTION John G. Jackson, Detroit, Mich, assignor to Square D Company, Detroit, Mich, a corporation of Michigan Application May 26, 1935), Serial No. 455,828

4 Claims.

This invention relates to switch constructions and more particularly to improvements in pressure switches.

One of the principal objects of this invention is to provide a switch of the type specified above in which a movable contact element in the form of a bar having an edge formed by the juncture of two intersecting plane surfaces is adapted to engage a cooperating stationary terminal to form a line contact therewith. Forming a line contact in this manner between the bar and terminal prevents flattening of the bar at the line of contact when pressure is applied, with the result that the area of the engaging portions is maintained at a minimum and a more intimate engagement is effected.

Another object of this invention is to provide a bar of the foregoing type so arranged relative to the terminal that movement thereof into engagement with the latter causes the edge forming the line contact to wipe or scrape along the terminal toward the center of the bar so as to prevent the edge aforesaid from biting or digging into the surface.

With the foregoing as well as other objects in view, the invention resides in the novel details of construction which will be made more apparent as this description proceeds, especially when considered in connection with the accompanying drawing, wherein:

Figure 1 is a semi-diagrammatic end view showing a switch constructed in accordance with this invention.

Figure 2 is a fragmentary sectional View through a portion of the switch showing the contact element in inoperative position.

Figure 3 is a view similar to Figure 2 showing the contact element in operative position.

Referring now to the drawing, it will be noted that there is illustrated semi-diagrammatically in Figure 1 a pressure switch 10 comprising a support 11 formed of a block of insulating material and constituting a mounting for a pair of cooperating terminals 12 and 13. The terminals 12 and 13 are in the form of substantially flat bars formed of a material having a relatively high co-efiicient of electrical conductivity and are spaced from each other longitudinally of the support. As shown in Figures 2 and 3, the terminal members 12 and 13 are supported in alignr and 13 to close the circuit with which the switch (Cl. 200-165) g is associated, I provide a flexible substantially straight contact bar 14. The bar 14 is supported within the space between the planes of the terminal members 12 and 13 upon a frame 15 having the opposite ends pivotally supported within the side walls 16 of the casing. The arrangement is such as to rockably support the contact bar '14 relative to the terminal members in sucha manner as to permit the latter to assume the positions illustrated in Figures 2 and 3. It will further be observed that the bar 14 is so mounted with respect to the terminal members 12 and 13 that when pressure is applied to the bar 14 to move the same to the position illustrated in Figure 3, the bar 14 is in effect fore-shortened with the result that the opposite end portions thereof slide along the terminal members 12 and 13 in a direction toward the pivotal mounting of the contact bar with the result that there is no tendency for the end portions of the bar to bite or dig into the terminal contact surfaces.

In order to obtain maximum efiiciency of the electrical contact between the ends of the bar 14 and the terminal contact members 12 and 13, the 4 bar 14 is provided with relatively sharp edge portions 17 and 18 formed by the juncture of the angularly arranged plane surfaces 17' and 18 and operable in the position of the parts shown in Figure 3 to form a line contact with the terminal members 12 and 13, respectively. By reason of the above construction, the area of the engaging portions of the contact members and terminals is infinitely small and does not increase when pressure is applied to the contact members with g the result that the efliciency of the connection is greatly increased since substantially all of the pressure applied to the contact members is concentrated over a relatively small area effecting a more intimate contact between the engaging surfaces.

For actuating the contact bar 14 to the positions illustrated in Figure 2 and 3, I provide a handle 19 operatively connected to the frame 15 through suitable pressure increasing mechanism which forms no part of the present invention and, as a consequence, will not be described herein. If desired, suitable arcing tips may be secured to the contact bar 14, as shown in Figures 2 and 3, in such a manner as to engage the terminal con- 5 tacts for dissipating to a certain extent the are caused by breaking the contact between the edges 17 and 18 of the bar and corresponding terminal contact members 12 and 13.

Thus, from the foregoing it will be observed that I have provided an improved pressure switch distinguished by its efiiciency in operation and simplicity in construction which permits the same to be manufactured economically and assembled with facility.

What I claim as my invention is:

1. In a switch of the class described, a pair of stationary terminal members spaced laterally apart in stepped relation and having substantially flat contact faces in substantially parallel planes, and means for establishing uniform and balanced line contact with the fiat faces of the terminal members aforesaid, comprising a single substantially straight contact bar of substantially uniform cross section throughout its length mounted intermediate of its ends for rotary movement and having transversely extending sharp right angular edges at opposite ends thereof engageable simultaneously with the fiat contact faces of said stepped terminal members.

2. In a switch of the class described, a pair of stationary terminal members spaced laterally apart in stepped relation and having substantially flat contact faces in substantially parallel planes,

and means for exerting uniform and balanced pressures against said flat contact faces to establish an electrical connection between said terminal members, comprising a single substantially straight contact bar of substantially uniform cross section throughout its length mounted intermediate of its ends for rotary movement and having transversely extending relatively sharp right angular edges at opposite ends thereof engageable simultaneously with the flat contact faces of said stepped terminal members, said bar being of such stiffness and constructed and arranged in such a Way relative to the fiat contact surfaces aforesaid that the balanced contact pressures exerted by the sharp edges at opposite ends thereof against said contact faces are transmitted solely through and by said bar.

3. In a switch of the class described, a pair of stationary terminal members spaced laterally apart in stepped relation and having substantially flat contact faces in substantially parallel planes, and means for obtaining balanced concentrated contact with the flat faces aforesaid of the terminal members, comprising a single substantially straight contact bar of substantially uniform cross section throughout its length mounted intermediate of its ends for rotary movement and having transversely extending sharp right angular edges at opposite ends thereof engageable simultaneously with the flat contact faces of said stepped terminal members, said bar being of such stiffness and arranged in such a way relative to the fiat contact faces aforesaid that the balanced contact aforesaid will be obtained solely by the engagement of the edges aforesaid of said bar with the flat contact faces of said terminal members.

4. In a switch of the class described, a pair of stationary terminal members spaced laterally apart in stepped relation and having substantially fiat contact faces in substantially parallel planes, and means independent of backers, reinforcements or plies for simultaneously engaging and exerting uniform and balanced concentrated pressures against the fiat contact faces of the terminal members, comprising a single substantially straight contact bar of substantially uniform cross section throughout its length mounted intermediate of its ends for rotary movement and having transversely extending relatively sharp edges at opposite ends thereof engageable simultaneously with the flat contact faces of said stepped terminal members.

JOHN G. JACKSON. 

